Cardiac ablation treatments involve the use of heat or freezing to create lesions in tissue for purposes such as restoring normal functioning of electrical activity near the tissue. Generally, cardiac ablation involves introducing a catheter into the heart where a therapeutic procedure can be carried out on abnormal heart tissue. Radio frequency (RF) ablation catheters employ electrodes at a distal end that can transfer RF or microwave electromagnetic energy to heart tissue. Catheter ablation is often used to treat atrial fibrillation and other types of heart rhythm disorders.
Common ablative treatment areas include the openings (or ostiums) of veins or arteries into chambers of the heart. For example, the ostium of the pulmonary vein is commonly treated by using an ablation catheter in the left atrium. While using an ablation catheter to treat ostium regions, the blood flowing from the vein or artery tends to cool the ablation electrodes. This cooling effect can sometimes make it difficult to deliver sufficient energy to create effective lesions.
Devices exist that can occlude the flow through blood vessels while ablation procedures are performed, and thereby diminishing the cooling effects. However, there are problems associated with occluding major vessels such as the pulmonary vein. Restriction of blood flow in these circulatory passageways for long durations of time can lead to complications in the patient. Therefore, use of full occlusion during ablation or other tissue procedures is necessarily time-limited. If the clinician cannot complete the procedure quickly, the occlusion devices must be regularly checked, engaged, and disengaged to allow some minimal amount of blood flow. This can add time and complexity to the ablation procedure.